Micro coating technologies

The innovative Combustion Chemical Vapor Deposition (CCVD) process, patented for applications other than the diamond coatings by the Georgia Institute of Technology and licensed exclusively to Micro Coating Technologies, Inc., (MCT, Chambiee, GA) has demonstrated its ability to overcome many of the shortcomings of traditional vapor... 

In chemical micro process technology with porous catalyst layers attached to the channel walls, convection through the porous medium can often be neglected. When the reactor geometry allows the flow to bypass the porous medium it will follow the path of smaller hydrodynamic resistance and will not penetrate the pore space. Thus, in micro reactors with channels coated with a catalyst medium, the flow velocity inside the medium is usually zero and heat and mass transfer occur by diffusion alone. 

Coating on micro structures is still dominated by manual coating techniques. For future automated production of catalysts and even complete reactors, automated coating procedures will become crucial. Some new approaches in coating technology especially suited for micro structures are described in Section 4.12.4, Online Reactor Manufacturing. 

Heatric claims to have developed a robust and renewable technology to apply catalyst coats to the passages within a PCR [163]. This coating has to be executed after the diffusion bonding but the coating procedure is not described. Such a development would certainly be a milestone in micro reaction technology as the standard wash-coat methods are usually applied to free accessible surfaces and not to closed channels. 

Wieder B, Brubaker C, GUnsner T, Kettner P, Nodes N (2002) Spray coating for MEMS, NEMS and Micro systems. Pacific Rim Workshop on transducers an micro/nano technologies... 

Process intensification and inorganic synthesis - including micro-reactor technology, membrane reactors sand catalyst coating. 

Bai A and Chen Z-J (2009), Effect of electrolyte additives on anti-corrosion ability of micro-arc oxide coatings formed on magnesium alloy AZ91D , Surface Coatings Technology, 203, 1956-1963. 

Cai, Q Z, Wang, L S, Wei, B K Liu, Q X (2006), Electrochemical performance of micro-arc oxidation films formed on AZ91D magnesium alloy in silicate and phosphate electrolytes . Surface Coating Technology, 200, 3727-3733. 

The implied capability of these plasma deposits to inhibit corrosion at metal surfaces may be of practical as well as of basic importance. An important consideration in this respect is the rapid rate of deposition for such protective coatings attainable at micro-wave frequencies. Since plasma technology is still in a process of evolution, optimum deposition kinetics cannot yet be stated however, the marked effect of excitation frequency on the deposition of organo-silicones can be documented (10), as in Fig. 3. Here, using terminology and comparative data due to Yasuda et al. (2). it is shown that deposition rates in microwave plasmas exceed those at lower (e.g. radio) frequencies by about an order of magnitude. 

Micro structured heat exchanger reactors offer unique capabilities of improving fuel processor performance as described in the sections above. However, manufacturing costs are currently considerably higher than for conventional mature technology. This will be overcome in the future with the application of cheap manufacturing and coating techniques suitable for mass production (see Sections 2.9 and 2.10), a procedure which is currently underway. 

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